Flat panel displays using liquid crystal display (LCD) technology are widely known and have found application in a number of fields for displaying visual information. In a flat panel LCD, the screen area, which is substantially rectangular, is divided into a large number of individual color dots. Each set of color dots is capable of displaying a full color gamut. It is known for the sets to comprise a three-dot combination of red, green and blue, a four-dot combination of red, green, green and blue, a four-dot combination of red, green, blue and white, and a six-dot combination of red, green, blue, yellow, cyan and magenta, as well as other combinations that allow a full color display. In an active matrix flat panel LCD, each color dot contains a transistor switch. A liquid crystal fluid, contained between a front plate and a rear plate, is twisted by a voltage which changes the axis of polarization of light, allowing the individual color dots to transmit or block light passing from a backlight source through the individual color filters. The color dots are arranged in a grid comprising rows and columns, and there can be several hundred or thousand vertical columns of color dots going across the display as well as hundreds or thousands of horizontal rows of color dots, resulting in most cases in more than 1,000,000 individual color dots. Each color dot has a vertical column and horizontal row grid address and is driven by electrical impulses fed along its respective row from a bus located on one of the side edges of the flat panel LCD and along its respective column from a top or bottom edge of the flat panel LCD. In general, the horizontal row drivers are referred to as gate drivers and the vertical column drivers are referred to as source drivers, but these may be reversed in practice, as will be known to those of skill in the art. In either case, the source driver signal provides the gray scale data for a given color dot, while the gate driver signal changes a given line of thin film transistors (“TFTs”) from “off” to “on” for a given “line time.” This signal from the gate driver thereby allows the charging of a capacitor associated with the individual color dot, determining the voltage held by the color dot for an entire frame period.
During the manufacture of a flat panel LCD, the panel that comprises the liquid crystal fluid and the front and rear plates contains flexible printed circuit elements that function as input and output for the gate, source, and heater driver circuit card assemblies. These circuit elements, or “tabs”, contain electrical contacts, or “pads”, that must be properly aligned with matching electrical contacts on each respective driver circuit card assembly in order for all the color dots to receive electrical signals and respond properly. An anisotropic, electrically conductive adhesive is typically used to make the electrical connection between the pads on the tabs of the LCD and the pads on each driver circuit card assembly, or “driver.” Alignment is key, as misalignment can result in a LCD display where parts of the screen are either partially or completely unresponsive to electrical signals, and is unsuitable for sale.
Furthermore, because LCD tabs are very fragile the process of aligning a tab with a driver can damage an LCD if the tabs are allowed to flex, shift, or rub against the drivers or other surfaces during the alignment process.
One previous attempt at aligning the LCD tabs to the drivers was done by placing tooling holes on both the LCD tabs and drivers such that when the LCD tabs were properly aligned over the drivers the tooling holes on the tabs and the drivers would line up. Electrical pads were located on both the tabs and drivers such that when aligned, the tooling holes would align as well, and pins could be driven through the holes to hold the LCD tabs and the drivers in proper alignment. However, this process has its disadvantages. The alignment of the tabs is difficult due to the delicateness and flexibility of the LCD tabs. Once in place the pins would stick and be difficult to remove without a substantial amount of prying, which had the potential to damage the tabs and drivers. Again, due to the fragility of the tabs, tabs could only sustain so much bending or damage before they would be considered useless under industry standards. For this reason this process often resulted in high product fallout. Furthermore, transportation of the LCD with tabs adhered to the drivers would also cause substantial damage to the tabs and reduce productive output due to unintended bending of the tabs due to handling.
The known art has failed to provide a device and method for properly aligning a LCD tab with drivers without damaging the LCD tabs or drivers. Furthermore, the known art has yet to provide a carrier for transporting a LCD with adhered tabs that have been aligned upon a driver.
An exemplary embodiment includes a retractable pin tool device for aligning a LCD panel with adhered tabs with driver circuit card assemblies. It is also an object of the exemplary embodiments to provide a retractable pin tool device for aligning a LCD panel with adhered tabs to with gate, source, and heater driver circuit card assemblies. An exemplary embodiment provides a method for aligning an LCD panel with adhered tabs to gate, source and heater driver circuit card assemblies using retractable pins.
Exemplary embodiments may comprise a base upon which a center platform and one or more pin blocks are attached. The center platform may be adapted to receive a first item. The pin blocks each have a plurality of pins that extend from their surface, and the pin blocks each have a means for retracting said pins into their surface. Handles may also be used in association with the pinion blocks to control the retraction and extension of pins. The pin blocks are located around the perimeter of the center platform such that when a first item is placed on the center platform, the pins may hold a second item in fixed position relative to the first item. In some embodiments the pins may hold the first item in place as well as a second item in place. Once it is no longer desired for the pins to hold one or more items in place, the pins may be retracted into the pin blocks. When the pins are retracted any item formerly held in place by the pins is released. In some embodiments the center platform may be adapted to receive an LCD panel that has adhered tabs.
The retractable pins may be used to hold gate, source, and heat drivers in fixed relative positions to the LCD panel and adhered tabs so that they can be bonded together or otherwise manipulated. The pins can hold these items in position while preventing shifting of the items and its damaging effects. Also, the pins can be retracted into the pin blocks without difficulty and without injuring the LCD panel assembly. Depending on the embodiment, different amounts of pin blocks may be present, the position of the pin blocks relative to the central platform may vary, and the location and number of pins on each pin block may vary.